Put the summary of the bug you're having here
What I expected to happen was...:
Spruce tree sapling grow to an adult tree for harvest
What actually happened was...:
Spruce tree sapling do not grow when placed in clusters.
Steps to Reproduce:
1. Place spruce tree saplings every 6 blocks apart
2. Wait for growth.
3. ...
It seems like a duplicate of MC-163403.